• 한국방사선학회논문지
• /
• 제7권3호
• /
• pp.227-232
• /
• 2013

엑스선 디지털 검출기의 내부 픽셀들은 조금씩 다른 감도와 오프셋 변동을 가지게 되어 불균일한 영상이 얻어진다. 이러한 문제를 해결하기 위해서 flat-field 보정 방법이 개발되었고, 이는 디지털 의료 영상 시스템의 전처리 과정에서 필수적으로 수행된다. 그럼에도 불구하고 여러 가지 이유로 균일하지 않은 영상이 획득되는 경우가 종종 발생한다. 본 연구에서는 디지털 의료 영상 장비에서 획득된 불균일한 영상에 flat-field 보정을 다시 적용시켜 화질이 개선되는 것을 확인하였다. 그리고 객관적인 화질의 평가를 위해 보정 전후의 NPS를 각각 산출하여 비교하였다. 주파수 영역에서 잡음의 변화를 분석한 결과 저주파수 성분의 잡음이 flat-field 보정 후에 크게 제거된 것을 확인할 수 있었다.

• 한국방사선학회논문지
• /
• 제4권1호
• /
• pp.25-30
• /
• 2010

이 연구 목적은 흉부영상의 진단에 적절한 해상력과 음영에 대한 적절한 평가를 위해서다. 해상력을 비교하기 위해서, linear 해상력 팬텀을 사용하여 film/screen(선생님이 원하시는 conventional radiography : film/screen), CR, DR, 촬영했다. 해상력을 비교하기 위해 2명의 영상의학과 전문의와 3명의 방사선사가 블라인드 테스트를 통하여 평가했다. DR 은 3.95 필름/ 스크린은 3.58, CR은 3.48의 평가가 나왔다. 음영에 대해 분석은, CR, DR의 film/screen의 정상적인 흉부영상 50장을 선택했다. 이 흉부영상에서 7부위(폐야, 폐야 윤곽, 종격동 I, 종격동 II, 심장 음영 I, 심장음영 II, 횡격막)을 정하여 덴시토미터(농도계)을 사용하여 음영을 평가했다. 우리의 분석 방법은 낮은 영상(음영)을 0에서부터 가장 우수한 영상(음영) 2를 정한 일본의 흉부 x-ray 평가 방법을 적용했다. DR의 경우 종격동 1, 종격동2, 심장 1, 심장2, 횡격막에서 2점을 기록하여 우수했다. 이와 반대로 CR에서는 폐부위와 폐음영 부위에서 2점으로 우수했다. 결론적으로, 해상력과 음영에 비교하면 후처리 알고리즘과 작은 픽셀 사이즈에 의한 DR은 CR과 film/screen 보다 우수하다고 도출하였다.

• Imaging Science in Dentistry
• /
• 제48권2호
• /
• pp.87-96
• /
• 2018

Purpose: The present study aimed to evaluate which of the following imaging methods best assessed misfit at the tooth-restoration interface: (1) bitewing radiographs, both conventional and digital, performed using a photostimulable phosphor plate (PSP) and a charge-coupled device (CCD) system; (2) panoramic radiographs, both conventional and digital; and (3) cone-beam computed tomography (CBCT). Materials and Methods: Forty healthy human molars with class I cavities were selected and divided into 4 groups according to the restoration that was applied: composite resin, composite resin with liner material to simulate misfit, dental amalgam, and dental amalgam with liner material to simulate misfit. Radiography and tomography were performed using the various imaging methods, and the resulting images were analyzed by 2 calibrated radiologists. The true presence or absence of misfit corresponding to an area of radiolucency in regions subjacent to the esthetic and metal restorations was validated with microscopy. The data were analyzed using a receiver operating characteristic (ROC) curve, and the scores were compared using the Cohen kappa coefficient. Results: For bitewing images, the digital systems (CCD and PSP) showed a higher area under the ROC curve (AUROC) for the evaluation of resin restorations, while the conventional images exhibited a larger AUROC for the evaluation of amalgam restorations. Conventional and digital panoramic radiographs did not yield good results for the evaluation of resin and amalgam restorations (P<.05). CBCT images exhibited good results for resin restorations(P>.05), but showed no discriminatory ability for amalgam restorations(P<.05). Conclusion: Bitewing radiographs (conventional or digital) should be the method of choice when assessing dental restoration misfit.

• 동력기계공학회지
• /
• 제15권4호
• /
• pp.25-30
• /
• 2011

This study is made to provide with a method for correcting the geometric distortion of the digital radiography image by analytical approach based upon the inverse square law and Beer's law. This study is aimed to find out and improve a mathematic model of nonlinear type. Variations in the alignment of the X-ray source, the object, and imaging plate affect digital radiography images. A model which is expressed in parameter values; e.g, angle, position, absorption coefficient, length, width and pixel account of radiography source, is developed so as to match the sample image. For the best correction of the digital image that is the most similar to the model image, a correction technique based upon tangent is developed; then applied to the digital radiography images of steel tubes. As a result, the image correction is confirmed to be made successfully.

• 제어로봇시스템학회논문지
• /
• 제7권3호
• /
• pp.246-254
• /
• 2001

In this paper, we described an approach to the automation of visual inspection of BGA solder joint defects of surface mounted components on printed circuit board by using neural network. Inherently, the BGA solder joints are located underneath its own package body, and this induces a difficulty of taking good image of the solder joints by using conventional imaging systems. To acquire the cross-sectional image of BGA sol-der joint, X-ray cross-sectional imaging method such as laminography and digital tomosynthesis has been cur-rently utilized. However, the cross-sectional image obtained by using laminography or DT methods, has inher-ent blurring effect and artifact. This problem has been a major obstacle to extract suitable features for classifi-cation. To solve this problem, a neural network based classification method is proposed int his paper. The per-formance of the proposed approach is tested on numerous samples of printed circuit boards and compared with that of human inspector. Experimental results reveal that the method provides satisfactory perform-ance and practical usefulness in BGA solder joint inspection.

• 대한디지털의료영상학회논문지
• /
• 제9권2호
• /
• pp.17-21
• /
• 2007

The purpose to recognize change of average pixel value of acquisition image by control panel's density and right set up method of speed (sensitivity) and exposure dose(mAs) change that dose in purpose digital flatpanel-detector. X -ray generator DHF-158H2(Hitachi, Japan). Detector CXDI 4OG(Canon, Japan), 12 : 1 grid and exposure ray 135 kVp, 250 mA, 10 ms. focus-detector distance 180 cm and used AEC mode. DICOM reflex analysis program used image J that is digital reflex analysis program that offer in United States America National Health Center(National Institutes of Health : NlH) phantom used chest phantom(Anthromorphic : Flukebrome.medicaI USA). An experiment chest phantom that consist by formation equivalence material use because density value( -3${\sim}$+3) in X-ray control panel and seep that is speed step(slow, medium, fast) each control experimentalize. image analysis reflex neted through an experiment using image j each image compare. These was change in dose according to slow, medium, fast and density's change in an experiment result. According to detector sensitivity and density condition set, dose was relationship dissimilarity 500% from 200%. The dose came highest when is density +3 to slow. and dose more increases gray scale's extent could know that rise. Could know whether how equipment set is important through this experiment. cause of disease which change by digital radiography system forward is thought to increase more, it is considered that suitable education by this and continuous interest about equipment need absolutely.

• 한국컴퓨터정보학회논문지
• /
• 제10권3호
• /
• pp.331-337
• /
• 2005

DICOM(Digital Imaging and Communications on Medicine) 표준은 2004년 4월에 발표된 "Supplement 23:DICOM SR(Structured Reporting)"을 통해 모든 임상정보의 표준화된 교환이 가능하도록 확장함으로써 의사의 판독보고서와 신체의 특정 부위와의 관계를 체계적으로 연결할 수 있게 되었다. DICOM SR은 정보를 정확하게 표현하기 위해 코드체계를 사용하며, 구성 항목들의 계층적인 트리로써 구조화된 정보를 표현할 수 있다. 본 논문에서는 병원정보시스템의 영상 판독결과 보고서를 분석하여 발견(finding), 결론(conclusion) 및 권고(recommendation)로 세분화하고 구조화한 후 실제로 의사가 진료에 활용할 수 있도록 DICOM SR 시스템을 구현하였다. X-ray와 같은 영상 데이터는 판독결과나 환자의 정보와 같은 텍스트 데이터와 별도로 관리되고 있다. DICOM SR로 표현된 판독결과 보고서는 영상에 대한 참조가 가능하므로 텍스트와 영상이 통합된 정보를 제공할 수 있다.

• Coupled systems mechanics
• /
• 제11권1호
• /
• pp.15-32
• /
• 2022

The comprehensive understanding of the fiber reinforced polymer behavior requires the use of advanced non-destructive testing methods due to its heterogeneous microstructure and anisotropic mechanical proprieties. In addition, the material response under load is strongly associated with manufacturing defects (e.g., voids, inclusions, fiber misalignment, debonds, improper cure and delamination). Such imperfections and microstructures induce various damage mechanisms arising at different scales before macrocracks are formed. The origin of damage phenomena can only be fully understood with the access to underlying microstructural features. This makes X-ray Computed Tomography an appropriate imaging tool to capture changes in the bulk of fibrous materials. Moreover, Digital Volume Correlation (DVC) can be used to measure kinematic fields induced by various loading histories. The correlation technique relies on image contrast induced by microstructures. Fibrous composites can be reinforced by different fiber architectures that may lead to poor natural contrast. Hence, a priori analyses need to be performed to assess the corresponding DVC measurement uncertainties. This study aimed to evaluate measurement resolutions of global and regularized DVC for glass fiber reinforced polymers with different fiber architectures. The measurement uncertainties were evaluated with respect to element size and regularization lengths. Even though FE-based DVC could not reach the recommended displacement uncertainty with low spatial resolution, regularized DVC enabled for the use of fine meshes when applying appropriate regularization.

• 대한디지털의료영상학회논문지
• /
• 제12권2호
• /
• pp.103-111
• /
• 2010

A total of 200 hospital employees participated in this study from January 2009 to June 2010. For the survey, each participant was given necessary items for external health exams. Cronbach's alpha was calculated for the survey regarding wireless networks. There was a need for educating data processing workers in the medical field regarding fundamental information prior to wireless network construction. The reason is high scores would be collected, which would reflect knowledge regarding data processing used at hospitals and the differences between paper charts and electronic charts. However, low scores were obtained which reflected knowledge regarding the differences between wired and wireless networks and Mini-PACS. Time for each patient was shortened to a maximum of three minutes and minimum of one minute for treatment and transmitting medical images when comparing pre and post wireless network construction(p < 0.01). Scores from the pre and post construction survey increase 1.98, 1.65, and 1.43 points for activity in the health screening area, usage of space in the health screening vehicle, and patient information storage respectively(p < 0.05). The number of patients receiving external health screenings twelve times was 3,655 prior to construction of a wireless network system. However, the number increased to 4,265 after construction. The increasing percentage was 17% in total. Prior to construction, X-ray images were taken 527 times, but after construction of a wireless network, this number growed to 1,194 and it was 116% increase. The loss of patient's medical treatment charts was reduced from 19.8% to 18.7% after construction. We believe that educating medical workers on Mini-PACS and Mini-OCS Systems will not only increase their efficiency but also make patients receiving better treatment.

• 대한디지털의료영상학회논문지
• /
• 제7권1호
• /
• pp.33-38
• /
• 2005

Modern hospitals have been greatly facilitated with information technology (IT) such as hospital information system (HIS). One of the most prominent achievements is medical imaging and image data management so-called Picture Archiving and Communication Systems (PACS). Due to inevitable use of diagnostic images (such as X-ray, CT, MRI), PACS made tremendous impact not only on radiology department but also nearly all clinical departments for exchange and sharing image related clinical information. There is no doubt that better use of PACS leads to highly efficient clinical administration and hospital management. However, due to rapid and widespread acceptance of PACS storage and management of digitized image data in hospital introduces overhead and bottleneck when transferring images among clinical departments within and/or across hospitals. Despite numerous technical difficulties, financing for installing PACS is a major hindrance to overcome. In addition, a mirroring or a clustering backup can be used to maximize security and efficiency, which may not be considered as cost-effective approach because of extra hardware expenses. In this study therefore we have developed a new based on grid of distributed PACS in order to balance between the cost and network performance among multiple hospitals.